1. Field of Invention
The present invention relates to an optical displacement detection apparatus and an optical displacement detection method; particularly, it relates to such optical displacement detection apparatus and optical displacement detection method which adaptively select auto-exposure range.
2. Description of Related Art
Among various applications of the optical displacement detection apparatus, the optical mouse is the most popular one. In an optical mouse, the light emitted from the light source is transmitted to and reflected by a surface such as the top of a desk, and the reflected light is received by a sensor chip embedded in the optical mouse. The sensor chip converts the optical signal to an electrical signal, and outputs the electrical signal to a processor. The processor calculates the electrical signal, to determine the displacement of the optical mouse.
Specifically, in the optical mouse, when the brightness of the surface is unevenly distributed, a dark zone will be formed. Even though the detected exposure state falls within the range of auto-exposure (AE), if the pattern to be tracked is in the dark zone, the sensitivity of the sensor chip to distinguish the pattern is reduced and it becomes difficult to extract correct features of the pattern. Accordingly, the calculation of the displacement tends to be incorrect due to the incorrectness of the obtained pattern features.
In view of the above, to overcome the drawbacks in the prior art, the present invention proposes an optical displacement detection apparatus and an optical displacement detection method. The present invention adaptively selects the AE range so that the optical displacement detection apparatus can track the pattern more accurately, thereby improving the accuracy of the displacement detection.